1. Field of the Invention
The present invention relates to disk drives for computer systems. More particularly, the present invention relates to a disk drive comprising a snap-on disk clamp.
2. Description of the Prior Art
Computer systems typically comprise a disk drive comprising one or more disks rotated about a center axis by a spindle motor, and a head actuated radially over the surface of the disk by a voice coil motor. The surface of the disk is coated with a magnetic material which is magnetized by the head in order to record digital data on the disk. The digital data modulates a current in a write coil of the head in order to write magnetic transitions representing the recorded data in concentric, radially spaced tracks. During read back, the head senses the magnetic transitions to generate an analog read signal comprising pulses representing the recorded digital data, wherein the pulses are demodulated into digital data transmitted to the host computer system.
The ability to accurately recover the recorded data is affected by several factors, including distortion (e.g., warping) of the disk as well as disk slippage. Disk warping can cause head fly height variations and distort the pre-written servo pattern, and disk slippage can degrade the servo system""s ability to maintain proper centerline tracking. It is therefore desirable to clamp the disk to the spindle motor in a manner that minimizes disk warping and disk slipping.
A ring-shaped disk clamp has been employed in prior art disk drives which is screwed onto the hub of the spindle motor by inserting screws through apertures in the disk clamp and fastening the screws to the hub of the spindle motor. The screws and associated fastening force are sparsely distributed around the circumference of the disk clamp (e.g., using six screws) which creates an uneven clamping force on the disk resulting in disk warping. In addition, the screws and associated apertures increase the manufacturing cost of the disk drive.
U.S. Pat. No. 5,940,244 discloses a shrink-fit disk clamp for a disk drive wherein a ring is expanded through heating, applied over the hub of the spindle motor onto the disk, and then cooled in order to shrink-fit the ring onto the hub. Shrink-fitting the disk clamp onto the hub provides a more evenly distributed clamping force on the disk as compared to the screw-down disk clamps. However, heating and cooling the disk clamp in order to achieve the desired shrink-fit installation requires expensive tooling and requires a cooling step during manufacture of the disk drive.
There is, therefore, a need for a more cost effective disk clamp for use in a disk drive which provides sufficient clamping force to minimize disk slippage as well as an evenly distributed clamping force to minimize disk warping.
The present invention may be regarded as a disk drive comprising a head, a spindle motor having a hub, the hub comprising a cylindrical shaft, the shaft defining a generally cylindrically-shaped outer surface, the outer surface defining a latching member extending around at least part of the circumference of the shaft. A disk is positioned on the spindle motor and an actuator moves the head radially over the disk. A disk clamp clamps the disk to the spindle motor. The disk clamp comprises a ring-shaped body comprising an outer ring-shaped surface abutting the disk, and an inner neck spaced-apart from the outer ring-shaped surface, the inner neck comprising a plurality of independently flexing teeth for contacting the latching member.
In one embodiment, the latching member comprises a groove extending around at least part of the circumference of the shaft, and each of the teeth comprise a tab inserted into the groove. In another embodiment, the latching member of the shaft comprises a protruding ridge extending around at least part of the circumference of the shaft, and each of the teeth comprises a groove interacting with the protruding ridge.
The present invention may also be regarded as a disk clamp for clamping a disk to a spindle motor of a disk drive. The spindle motor comprises a hub, the hub comprises a cylindrical shaft, the shaft defining a generally cylindrically-shaped outer surface, the outer surface defining a latching member extending around at least part of the circumference of the shaft. The disk clamp comprises a ring shaped body comprising an outer ring-shaped surface abutting the disk, and an inner neck spaced-apart from the outer ring-shaped surface, the inner neck comprising a plurality of independently flexing teeth for contacting the latching member.